This invention relates to electronradiography and in particular, to X-ray systems providing for real time imaging.
Present methods of real time imaging of X-rays are unsatisfactory for a variety of reasons. Fluoroscopy requires a high dosage of X-rays, has relatively poor resolution and requires dark adpatation for the viewer. In order to overcome the last limitation, image intensifying tubes are employed. Such tubes produce a small bright image which has to be viewed using either magnifying optics or a television chain, either being a relatively complex setup. The size of the area being observed is limited by the size of the intensifier tube.
It is an object of the present invention to provide a new and improved X-ray imaging system which can be used for real time imaging. A further object is to provide such a system utilizing electronradiography for the formation of an electrostatic charge image with an improved imaging chamber for converting the electrostatic charge image to a visible image.
In the conventional electronradiography system, a dielectric receptor sheet is positioned at an electrode surface in a gap between a pair of electrodes. An X-ray absorber and electron and positive ion emitter is maintained in the gap between the electrodes. A source of X-rays is directed to the gap past the object being X-rayed, and incoming X-ray photons generate electrons and positive ions in the gap which are attracted towards the respective electrodes. Charges are collected on a dielectric receptor sheet providing a latent electrostatic charge image of the object, and this image is then developed to a visual image by standard xerographic techniques with the density of the deposited toner powder particles being a function of the magnitude of the electrostatic charge. An electronradiography system utilizing gas as the absorber is shown in U.S. Pat. No. 3,774,029. An electronradiography system utilizing liquid as the absorber is shown in copending application Ser. No. 456,532, filed Apr. 1, 1974, now U.S. Pat. No. 3,873,833 and assigned to the same assignee as the present application.
It is an object of the present invention to provide a new and improved electronradiography system for producing a directly viewable image at the imaging chamber utilizing the electrostatic charge image for creating the visual image, while omitting the receptor sheet and the time required for converting the charge image on the receptor sheet to a visible image. A further object is to provide such a system wherein the visible image is formed directly in the imaging chamber substantially simultaneously with the X-ray exposure, providing real time imaging. A further object is to provide such a system wherein the X-ray exposure and image viewing sequence may be repeated cyclically at a relatively high rate, such as in the order of 10 to 20 images per second, resulting in a substantially continuous image for the viewer.